Mailboxes of the type associated with rural delivery addresses, may be located next to the side of a road, so that the mail can be delivered to such boxes by means of a motor vehicle . . . typically without the mail carrier even getting out of the vehicle. The roadside mailbox is generally thus some distance from the quarters actually intended for the mail. With unpredictable schedules of even mail carriers, it is not uncommon for someone to walk to a distant mailbox . . . only to find it empty . . . because the mail had not yet been delivered that day.
Devices may be used on roadside mailboxes, to signal when the mailbox door has been opened. Such devices frequently may use a flag that normally upstands from the mailbox, held there resiliently by a spring or a counterbalance; but the flag may be shifted to a lowered position, against the force of the spring or counterbalance. Some form of catch may be used to hold the flag lowered, being triggered by the door being opened to release the flag to the upright position.
Many of such known signal devices typically may not be easily mounted on the mailbox, without using tools, or without irreversibly altering the mailbox... such as by drilling mounting holes in it. Moreover, once in place on the mailbox, many such signal devices may require that two hands be used to lower and set the flag, such as possible upon simultaneously closing the mailbox door. Also, many signal devices, when mounted on the mailbox, face toward the front of the mailbox, to provide only a partical profile of the signal flag from any side angle of viewing, such as may be required if the mailbox is to be viewed from the intended quarters.
The following identified U.S. Patents illustrate different forms of mailbox signal devices, including U.S. Pat. No. 2,433,940 issued to H. M. Weaver; U.S. Pat. No. 2,874,895 issued to F. W. Opp et al; U.S. Pat. No. 3,490,411 issued to M. C. Poindexter; U.S. Pat. No. 3,596,631 issued to D. F. Sutton; U.S. Pat. No. 3,866,823 issued to R. E. Grayson; U.S. Pat. No. 4,000,847 issued to J. L. Duls; and U.S. Pat. No. 4,138,056 issued to J. T. Sherrill.